Keyword stuffing was considered to be an unethical search engine optimization (SEO) technique. Keyword stuffing occurs when a web page is loaded with keywords in the meta tags or in content. The repetition of words in meta tags may explain why many search engines no longer use these tags.

Keyword stuffing had been used in the past to obtain maximum search engine ranking and visibility for specific phrases. This method is completely outdated and adds no value to rankings today. In particular, Google no longer gives good rankings to pages employing this technique.

Hiding text out of view of the visitor is done in many different ways. Text colored to blend with the background, CSS "Z" positioning to place text "behind" an image – and therefore out of view of the visitor – and CSS absolute positioning to have the text positioned far from the page center, are all common techniques. As of 2005, some of these invisible text techniques can be detected by major search engines.

"Noscript" tags are another way to place hidden content within a page. While they are a valid optimization method for displaying an alternative representation of scripted content, they may be abused, since search engines may index content that is invisible to most visitors.

Inserted text sometimes includes words that are frequently searched (such as "sex"), even if those terms resemble little connection to the content of a page, in order to attract traffic to advert-driven pages.

In the past, Keyword stuffing was considered to be either a white hat or a black hat tactic, depending on the context of the technique, and the opinion of the person judging it. While a great deal of keyword stuffing was employed to aid in spamdexing, which is of little benefit to the user, keyword stuffing in certain conditions was not intended to skew results in a deceptive manner. Whether the term carries a pejorative or neutral connotation is dependent on whether the practice is used to pollute the results with pages of little relevance, or to direct traffic to a page of relevance that would have otherwise been de-emphasized due to the search engine's inability to interpret and understand related ideas. This is no longer the case. Search engines now employ themed, related keyword techniques to interpret the intent of the content on a page.